Investigating the causal relationship between physical activity and incident knee osteoarthritis: a two-sample Mendelian randomization study.

There is evidence that physical activity (PA) has a long-term positive impact on disease. Whether PA is a risk factor for knee osteoarthritis (OA) is still controversial. The purpose of this study was to explore whether there is a causal relationship between PA and knee OA. We extracted PA and knee OA data from genome-wide association study (GWAS) databases. We used single-nucleotide polymorphisms (SNPs) as instrumental variables. We performed MR analysis by random-effects inverse-variance weighting (IVW), MR‒Egger, weighted median, simple mode, and weighted mode methods. We evaluated the stability and reliability of the results through sensitivity analysis. There was no significant association between PA and knee OA (p > 0.05). We did not detect any pleiotropy (MR‒Egger intercept test et al.: p > 0.05). The sensitivity analysis confirmed our results (p > 0.05). There is no causal relationship between PA and knee OA.

Intestinal Continuity Alleviates Pediatric Intestinal Failure-Associated Liver Disease.

Background: Type I short bowel syndrome (SBS) occurs after a critical reduction in the functional gut mass and resection of intestinal continuity after ileostomy or jejunostomy for necrotizing enterocolitis (NEC), intestinal atresia or other causes. SBS is often accompanied with intestinal failure-associated liver disease (IFALD) who requires long-term parenteral nutrition (PN). Our study aimed to observe the effect of intestinal continuity on the hepatic function of pediatric intestinal failure (IF) patients with type I SBS. Methods: The pre-and post-anastomosis medical records of 35 pediatric patients with type I SBS from April 2013 to April 2019 were reviewed retrospectively. The average growth (cm/month) in the proximal and distal small bowel lengths was calculated as the growth in intestinal length (cm)/the duration (month) from enterostomy to anastomosis. The changes in hepatic function from enterostomy to anastomosis were evaluated by assessment of hepatic function before anastomosis for 6 weeks and after anastomosis for 4 weeks. Results: The average growth in proximal intestinal length was 9.3 cm/month (±7.2) in neonates and 2.8 cm/month (1.3, 11.9) in infants and children, and in distal intestinal length was 1.5 cm/month (0, 2.7) in neonates and 0.4 cm/month (0, 1.4) in infants and children. The incidence of IFALD was 28.6% 1 month before anastomosis and 20.0% 1 month after anastomosis (p < 0.05). Conclusion: In pediatric type I SBS with IFALD, restoration of intestinal continuity may alleviate liver injury. There was an intestinal compensatory effect on the growth in the intestinal length after resection, and better results were seen in neonates in terms of intestinal length growth.

Oxidosqualene Cyclases Involved in the Biosynthesis of Diverse Triterpenes in Camellia sasanqua.

Camellia sasanqua is an important economic plant that is rich in lipophilic triterpenols with pharmacological activities including antiallergic, anti-inflammatory, and anticancer activities. However, the key enzymes related to triterpene biosynthesis have seldom been studied in C. sasanqua. Oxidosqualene cyclases (OSCs) are the rate-limiting enzymes related to triterpene biosynthesis. In this study, seven putative OSC genes (CsOSC1-7) were mined from the C. sasanqua transcriptome. Six CsOSCs were characterized for the biosynthesis of diverse triterpene skeletons, including α-amyrin, ß-amyrin, δ-amyrin, dammarenediol-II, ψ-taraxasterol, taraxasterol, and cycloartenol by the heterologous expression system. CsOSC3 was a multiple functional α-amyrin synthase. Three key residues, Trp260, Tyr262, and Phe415, are critical to the catalytic performance of CsOSC3 judging from the results of molecular docking and site-directed mutagenesis. These findings provide important insights into the biosynthesis pathway of triterpenes in C. sasanqua.

Transcriptome Analysis and Identification of the Cholesterol Side Chain Cleavage Enzyme BbgCYP11A1 From Bufo bufo gargarizans.

Bufo bufo gargarizans Cantor are precious medicinal animals in traditional Chinese medicine (TCM). Bufadienolides as the major pharmacological components are generated from the venomous glands of B. bufo gargarizans. Bufadienolides are one type of cardiac aglycone with a six-member lactone ring and have properties of antitumor, cardiotonic, tonsillitis, and anti-inflammatory. The biosynthesis of bufadienolides is complex and unclear. This study explored the transcriptome of three different tissues (skin glands, venom glands, and muscles) of B. bufo gargarizans by high-throughput sequencing. According to the gene tissue-specific expression profile, 389 candidate genes were predicted possibly participating in the bufadienolides biosynthesis pathway. Then, BbgCYP11A1 was identified as a cholesterol side chain cleaving the enzyme in engineering yeast producing cholesterol. Furthermore, the catalytic activity of BbgCYP11A1 was studied with various redox partners. Interestingly, a plant NADPH-cytochrome P450 reductase (CPR) from Anemarrhena asphodeloides showed notably higher production than BbgAdx-2A-BbgAdR from B. bufo gargarizans. These results will provide certainly molecular research to reveal the bufadienolides biosynthesis pathway in B. bufo gargarizans.

Transcriptomic investigation of the biochemical function of 7-dehydrocholesterol reductase 1 from the traditional Chinese medicinal plant Anemarrhena asphodeloides Bunge.

Anemarrhena asphodeloides Bunge (Liliaceae) is an important Traditional Chinese Medicine herb, which contains up to 6 % total steroidal saponins (timosaponins) and has multiple pharmacological properties. However, the timosaponin biosynthetic pathway has not been extensively investigated. Here we conducted de novo transcriptome sequencing and analysis of A. asphodeloides Bunge and screened for candidate genes involved in the timosaponin biosynthetic pathway. Targeted metabolite analysis showed that timosaponins primarily accumulated in rhizomes, while phytosterols (including cholesterol) were distributed throughout various organs. Most of the identified candidate genes of the timosaponin biosynthetic pathway were also highly expressed in the rhizome, consistent with the results of metabolic analysis. Based on the transcriptome results, two candidate 7-dehydrocholesterol reductase genes were cloned and heterologously expressed in the yeast Saccharomyces cerevisiae. The purified and identified products supported that Aa7DR1 possessed Δ7-reduction activity in yeast and therefore may be involved in the timosaponins biosynthetic pathway in A. asphodeloides Bunge. Phylogenetic analysis showed Aa7DR1 belongs to monocotyledonous Δ7 reductase of phytosterol biosynthesis. These data expand our understanding of timosaponin biosynthesis.

Alterations of gut microbiota and serum bile acids are associated with parenteral nutrition-associated liver disease.

BACKGROUND: Parenteral nutrition-associated liver disease (PNALD) is a major complication of long-term parenteral nutrition (PN). The pathogenesis of PNALD remains unclear. We investigated the changes in taxonomic and functional composition of gut microbiota and serum bile acid levels in a rat model of PNALD. METHODS: Male 4-week-old Sprague Dawley rats received either total parenteral nutrition or standard chow with 0.9% saline for 7 days. The taxonomic composition of cecal microbiota and its functional composition associated with bile acid metabolism were measured. RESULTS: There were differences in taxonomic composition between the two groups. The abundance of the secondary bile acid biosynthesis pathway was higher in the TPN group (p < 0.05) with an increase in the percentage of bacteria expressing 7-alpha-hydroxysteroid dehydrogenase (p < 0.05). The abundance of enzymes associated with bile salt hydrolase was also higher (p < 0.05) in the TPN group. The TPN group showed a distinct bile acid profile characterized by a higher ratio of secondary bile acids to primary bile acids. CONCLUSIONS: The alteration of bile acid-associated microbiota may lead to increased secondary bile acid production in a rat model of PNALD.